(a) The Field of the Invention
This invention relates to the production of synthetic polyamide filaments and fibers having high flame-resisting properties.
(b) The Prior Art
It is known how to confer flame-resistance to textile materials in general by introducing additives therein, such as nitrogenous compounds, phosphorus compounds, etc. A class of additives utilized are the derivatives, e.g. the salts, of melamine (triaminotriazine), and among these salts, the salt of isocyanuric acid (trioxytriazine) is included.
Czechoslovakian Pat. No. 127,854 discloses a method for making textile materials flame-resistant by impregnation with condensation products of various derivatives of s-triazine, in particular melamine isocyanurate. However, that process has considerable shortcomings, and in particular it not only requires a laborious finishing treatment, but the flame-resisting effect to be obtained is inadequate and insufficiently stable through the life of the manufactured article, especially with regard to the washing to which it will be subjected, as necessary. It would be conceivable to add the flame-retarding additive to the molten polyamide, but since the former is insoluble in the latter, it is impossible to achieve a homogeneous clot-free dispersion, as a polymer suitable for spinning would require.
Thus, still unknown in the art are successful methods for obtaining fibers and yarns which have flame-resisting properties due to the presence therein of the derivatives of s-triazine according to the cited Czechoslovakian patent.